Anti-phospholipid antibodies in patients with multiple sclerosis and MS-like illnesses: MS or APS?

Objective: To describe the frequency, clinical, and laboratory features of patients diagnosed with multiple sclerosis (MS) or MS-like illnesses (MSL) among a large, prospectively followed cohort of anti-phospholipid antibody (aPL)-positive patients. Methods: Between 1990 and 1995 patients referred to a university-affiliated rheumatology clinic were prospectively evaluated for aPL based on question naires designed to detect aPL-related symptoms and/or a family history of a PL-related illnesses. Magnetic resonance imaging (MRI) was performed when s ignificant neurological features were present. A subgroup of all patients d iagnosed with MS or MSL was identified and their clinical, laboratory, and imaging findings were reviewed. Results: Of 322 patients evaluated for aPL-related symptoms or events, 189 (59%) were positive for at least one class of aPL. Twenty-six of 322 patien ts (8%) carried a diagnosis of MS or MSL, either at the initial evaluation or during the study period. Twenty-three of the 26 individuals (88%) tested positive for aPL, while the remaining 3 (11%) tested repeatedly negative. Eighteen of the 23 patients (78%) had either more than one class of aPL or had multiple positive titers. IgM aCL was noted in 18 of the 23 patients (7 8%). Oligoclonal bands were noted in five patients. Antinuclear antibodies (ANA) and low complement levels were frequently observed. Blinded MRI readi ngs showed lesions consistent with MS in the majority of cases. Clinically, 7 patients had transverse myelitis (TM), while optic neuritis (ON) was pre sent in 8 patients. Most patients had either occult symptoms of rheumatic d isease or contributory family histories. None had a defined underlying conn ective-tissue disease. Conclusion: A substantial number of aPL-positive patients have a concurrent diagnosis of MS or MSL, frequently presenting with elevated IgM aCL, optic neuritis, and transverse myelitis. The anti-phospholipid syndrome (APS) sh ould be strongly considered as an alternative diagnosis to MS in these pati ents.